Emergency vehicles are typically equipped with lights that serve to inform the public of their status. For example, police vehicles in the United States use flashing blue lights on their roofs, and in some cases on their dashboards. Additional indicators can be provided with flashing headlights and taillights. However, the sides of these vehicles are not equipped with any easily seen warning lights.
The lack of warning indicators on emergency vehicle sides has been known to be at least partially responsible for side, so-called “T-bone,” collisions in intersections, if another vehicle is entering an intersection through which the emergency vehicle is passing. Another dangerous position for emergency vehicles is alongside a road, where passing motorists can fail to see the emergency vehicle in time to avoid a collision.